Quantum Instruments Cascade Laser Starter Kit DFB and FP Quantum Cascade Lasers, Description

Starter Kit Instruction Manual Description 13

4.3 DFB and FP Quantum Cascade Lasers

4.3.1Description

Quantum Cascade Lasers (QCL) are unipolar lasers emitting in the mid-infrared from 4 to 17 microns. The laser is a ridge of InGaAs and AlInAs grown on InP providing gain and a Fabry-Perot cavity in order to build the laser oscillation up. Distributed- Feedback(DFB) Quantum Cascade Lasers are then obtained by adding a grating, forcing the laser to emit at the target wavelength.

4.3.2Geometry of QC lasers

Mountings

Lasers exist in two different packages:

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Fig.3: ST submount

•ST mounting (1)

•NS mounting (2)

Axes of QC lasers

The vertical direction is the so called growth direc- tion.

Device are mounted on a copper carrier which has one or two ceramic pads carrying the bonding wires. The pads are yellow on top due to a layer of gold, and white around it and on the sides (colour of the ceramic). If these pads are placed upwards, the vertical for the laser is the same as the observer vertical direction.

If there are two ceramic pads present, they are named as follows:

Looking onto the front facet with the laser placed as described above, the pad left of the laser chip is called ”DN” (for DOWN), the one on the right of it ”UP”.

If no configuration is specified, the ”DN” pad is used.

Never place the laser upside-down, since this will damage the bonds connecting the pads to the laser and possibly the laser itself!

The laser chips mounted on NS submounts pro- vided separately from a LLH100 are supplied in a round plastic box. For removing the laser from it, please follow the instructions as described in ap- pendix (appendix 10.2, p.59)

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Fig.4: NS submount